I'm trying to route dynamo wiring inside the fork blade using the existing vent holes: one at the dropout and one at the crown, drilled through the steerer tube. I have determined that the two-conductor wiring will fit through each hole just fine, and I can snake the wiring all the way through the fork blade, but here is the dilemma: I can't snake the wiring out the other end.

I have a lot of experience snaking wires through tight spaces, walls, and other difficult junctions (I used to do custom home theater and car audio wiring), but this one has got me stumped. I have been able to snake different wires of varying stiffness through the fork blade, but I simply can't get any wire to "find" the exit hole, which is at a 90 degree angle to the blade. See the photos:

top hole, exiting from the fork crown into the steerer tube. Very difficult to feed the wire into, because the wire has to bend 180 degrees to work its way down the fork blade:

bottom hole, exiting the fork blade at the dropout. This is the one that is easy to feed the wire through:

In the photos, I'm snaking picture hanging wire, which is stiff but bendable. I can snake it or the dynamo wiring all the way up the blade until it hits the crown. I can not snake it the other way around, through the steerer tube hole, but I feel that if I can get it around the sharp bend at the crown, and get it to snake downward through the fork blade, it will be easier to exit at the bottom, because if I can see the wire through the vent hole, I can use micro-sized surgical tweezers to grab it and pull it out. I can't do that from the steerer tube because it's impossible to get a tool into that exit hole.

I'll look at work for some fancy OR tweezers or hemostats. I know I have one pair of hemostats that have a 90 degree bend in them. I'm planning something similar myself so if it works for me, I'll send you a set

Have you tried doing the trick with the vacuum and string that people use for routing internal cables? Then you might just be able to pull the wire through with the string. That is a small hole near the dropout, but I think you might be able to use the string trick.

I'll look at work for some fancy OR tweezers or hemostats. I know I have one pair of hemostats that have a 90 degree bend in them. I'm planning something similar myself so if it works for me, I'll send you a set

Rob, I have two-conductor, 24-gauge OFC copper wiring for the dynamo wiring. It has a thin insulating sheath, so it fits fine. I also have nice cylindrical coaxial cable that fits. I'm not concerned with getting any particular cable through, because anything I manage to route successfully can be soldered to my wiring of choice, and used to pull it through.

I actually have that mini-grabber, and it's way too big!

Quote:

Originally Posted by Ciufalon

Have you tried doing the trick with the vacuum and string that people use for routing internal cables? Then you might just be able to pull the wire through with the string. That is a small hole near the dropout, but I think you might be able to use the string trick.

I've never tried that trick, but I've heard of it and am unclear on the details. How does it work? I assume you apply vacuum to one end while slowly feeding loose string through the other end? Is it that the high velocity of air flowing through the fork blade pulls the string through? I have access to strong vacuum spigots at the lab; I can concentrate way more vacuum onto either of those holes using a section of lab PVC tubing than I possibly could using a vacuum cleaner hose! What type of narrow string would you suggest? It might actually be easy to feed string in through the steerer tube hole because it's so floppy.

attach a small piece of a magnatized paperclip to one end of the wire (soldier it on, then magnatize it, otherwise the heat will de-magnatize it)
then try to pull it through the fork using a really strong magnet on the outside of the fork, dragging it along the length of the blade (from crown to dropout) hopefully pulling the piece of paperclip and wire along with it.

(I used to do this with a magnet and a coin in grade school through my desk, the coin moves without being touched)

if you could create enough force, you could drag the wire through the blade and then try to get it out at the dropout end. I've never tried it on steel or in such a small space but in theory it could work.

Search in the mechanics forum for internal cable routing and there are instructions on how to use the vacuum/string trick as well as other ecommendations. Basically, you feed a string in the easy end and then apply a vacuum with your hand cupped around it to the other end to suck it out the hole. You can then use the string to attach to your wire and pull it through to the other end. If you have a small housing you can use, you can feed that on the string until it is out both ends and then feed the wire through that. At that point, whenever you need to change either the wires or the housing, you do one or the other first, using the other, which is still in place to feed it on or through.

I typically use a single strand of a brake or shifter cable. Make a loop at one end and feed it up through the hole. You can pinch the top of the loop so it will feed through the hole easily. You also need something to hook the loop at the top. When running a wire from one small hole to another I will make a hook out of a second cable strand, but in this instance there may be something better suited for the job. Once you have the cable strand fed through, attach the unjacketed copper wire to the end of the cable strand and gently pull it through.

you have the pic wire run through the blade yes? why can't you sodder the 24g wire to it and slowly pull it through?

The problem is that it's not through both holes. The pics show it being fed through one hole or the other, but I can't get it out the other end. You're right, once I have it through all the way I can solder my wire of choice to it and pull it through.

1) Tie a needle to some thread then cut the needle so that the only thing remaining is the threaded eye.
2) Drop it into the smaller hole near the front drop out.
3) finda way to stuff a small magnet into the hole at the crown and still be able to retrieve it. (Maybe stick a magnetized screwdriver into the hole)
4) Turn the fork upside-down, shake it around and pulll out the magnet and hopefully the needle head will be stick to it along with the thread.

1) Tie a needle to some thread then cut the needle so that the only thing remaining is the threaded eye.
2) Drop it into the smaller hole near the front drop out.
3) finda way to stuff a small magnet into the hole at the crown and still be able to retrieve it. (Maybe stick a magnetized screwdriver into the hole)
4) Turn the fork upside-down, shake it around and pulll out the magnet and hopefully the needle head will be stick to it along with the thread.

Wow, some great ideas in this thread. I knew I could count on you peeps.

I will vote for the vacuum method, especially seeing how you have access to a lab vacuum line. I have used that technique mainly for fishing a line for power cables, but I don't see why it wouldn't work here. I would use a sewing thread (the heavier the better) and tie a knot on the leading end of it. I think you would have problems with a magnet due to the amount of steel surrounding the area. I was wondering about using a stiff thin wire and bending a 180* in it as you started from the bottom, then grabbing the top with a set of small forceps, that would be my first choice, quickly followed by the vacuum. But I am lazy and don't feel like going and digging out the parts for the vacuum either.

Aaron

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I build motorcycles for a living.....well I used to. The vacuum and string method is best. Finding the right kind of string is the hard part. I used fluorescent orange stuff used by a customer who was a surveyor. Sometimes filing the holes to remove burrs and sharp edges is needed. Having said that running wiring internally is aesthetically pleasing it's also asking for problems. Be willing to do it a few times during the life of the bike.

I would take a thin guitar string... high E, presumably; bend it in half and form the bent end into an eyelet a little smaller than the inside of the fork crown (you have to imagine this shape to the best of your abilities). Then squeeze that into the hole. It should open up inside the tube. Then push your electric wire up from the dropout end. When it's gone as far as you can make it go, it should be through the guitar string; so now twist and pull the guitar string out. It will close up around the wire and, hopefully pull it through the hole.

are you really snaking into the fork blade at the top? I wouldn't have thought there was any reason to make a big enough hole in the blade up there to allow this. The reason for the hole in the steerer is because the crown itself needs to be vented. I'm going to build a fork for the new Schmidt dropouts with the built-in dyno contacts. I think I will just run tubing the correct size the length of the fork. Seems like it avoids this problem altogether.

I'm going to build a fork for the new Schmidt dropouts with the built-in dyno contacts. I think I will just run tubing the correct size the length of the fork. Seems like it avoids this problem altogether.

You mean like an internal conduit? Or external? An internal conduit would be perfect.

Quote:

Originally Posted by unterhausen

are you really snaking into the fork blade at the top? I wouldn't have thought there was any reason to make a big enough hole in the blade up there to allow this. The reason for the hole in the steerer is because the crown itself needs to be vented.

This would be my understanding as well-- to vent the crown and/or the fork blade. However, most of my bikes don't have this steerer vent hole! Neither of my bikes with Reynolds fork blades have it (Raleigh Comp and Jeunet 630), and my Trek 560 with Trek fork crown and tru-temper fork blades doesn't have it. So far, only my Tange fork blade bikes have this vent hole in the steerer tube. The Reynolds fork blades do have an upper and lower vent hole, but the vent holes are strictly on the blades, not the crown or steerer tube.

And yes, the the wire is definitely snaking into the blade. Two pieces of evidence indicates this: 1) if I blow compressed air into the lower hole, it comes out the upper hole, and with very little resistance; 2) I can successfully snake a derailleur housing liner into the steerer hole and feed it until it stops near the bottom of the blade. When I pull it back out and measure how much was inserted, it corresponds to almost the entire length of the blade. I think it's getting hung up near the bottom where the blade tapers narrower, and is probably getting hung up on the tacky frame saver I applied inside the fork blades (I know, I should have waited until after I snaked the wiring through!). When I feed a wire or liner through the lower vent hole, it goes all the way up to the crown.

Feed a wire from the bottom to the fork crown. When it gets to the top, use another wire with a hook or loop in it to snag the end of the first wire to coax it through the hole at the crown. It may be best to use thin single strand wire from the bottom. Put a small hook in the end. This will make it easier to snag with the bent wire from the top.

UPDATE: I got it! After hours of wrangling with a dozen different thicknesses and stiffnesses of wires, and putting everyone's ideas to the test, the KEY tip was provided by USAZorro:

Quote:

Originally Posted by USAZorro

Tie about 5" of thread about 1/2" from the end of the wire you're feeding in through the weep hole. Push the wire all the way in, suction the thread, and then pull the wire out using the thread.

Initially I tried the thread and vacuum trick, but not tied to the end of a stiffer wire. The vacuum was capable of sucking the thread into the fork blade just fine, but the thread would just get hung up somewhere in the fork blade, all bunched up as the vacuum would keep sucking more in.

I ended up taping about 5" of thread to the end of a single strand of derailleur cable. The cable strand easily fed through the length of the fork blade up to the fork crown, but then hit the crown and wouldn't budge further. But with the short piece of thread taped to the end, the vacuum was able to pull that short piece through the fork crown hole. I then tied a long piece of strong quilting thread to the end of the short 5" section of thread, and fed it through the fork blade by pulling out the derailleur cable strand.

Man, I was almost going to give up after several hours of frustration, and resort to zip ties to hold the dynamo wire to the fork externally, but in the end, the strategy worked. Perseverance pays off!

I hope you don't mind me going off topic since you've solved your problem now. Does anyone know what kind of wiring is used for bike computers? I would love to route my bike computer this way and avoid the ugly fork wire, etc. If it's just a simple one strand wire or something I wouldn't be too worried about cutting it and reattaching in order to get it through the holes.